Intraocular lenses (IOL's) are a well-known type of surgical implant used to replace the natural lens of an eye which has been damaged as a result of trauma or disease. Such IOL's typically comprise an optic and at least one fixation member attached to the optic. The fixation member functions to position the optic in the correct optical alignment within the eye. Many fixation members are of filamentary form, and are attached to the optic at or near the periphery of the optic.
It is conventional practice to construct the optic of a hard biocompatible polymer, such as polymethylmethacrylate (PMMA). More recently, it has been proposed to construct the optic from a relatively flexible or deformable material. When so constructed, the optic can be rolled or flexed into a relatively small cross-sectional configuration to permit it to be inserted through a relatively small incision into the eye to thereby reduce trauma and the likelihood of infection from the surgery.
The fixation members are constructed of a resilient material, typically polypropylene. In some IOL's, the fixation members are integrally formed with the optic. In other types of IOL's, various methods of attaching the fixation members to the optic have been devised.
The attachment of the fixation members to the optic is particularly troublesome when the optic is constructed of soft or deformable material, such as silicone. For example, when the deformable optic is folded or rolled prior to insertion through the incision into the eye, flexure of the optic creates a likelihood that the fixation members will become detached from the optic. Also, forces on the fixation members resulting from insertion of the IOL through the incision or from pulling on the fixation members to adjust the IOL after insertion, creates a likelihood that the fixation members will become detached from the optic. If this occurs, it not only renders the IOL useless, but also is a potential hazard to the patient. The soft optic materials, such as silicone, do not have sufficient rigidity to be used an integral fixation member or haptic.